Presently, other than the hydroelectric process, the main sources of electric power begin with the burning of hydrocarbons to create heat, the fission of radioactive elements to create heat, or the tapping of the earth's latent heat. These processes all have in common the concept of utilizing heat to generate electricity. The heat is commonly used to boil water to create steam which expands to drive steam turbines or engines which in turn drive electric generators. These usual processes require two steps and result in conversion efficiencies of typically 5 to 35 percent. Far greater efficiencies could be achieved with a one step process wherein thermal radiation from a heat source would be converted directly to electricity.
Marks, in U.S. Pat. No. 4,445,050, discloses such a one step process. Marks shows the use of a dipole antenna for receiving light photons and converting them directly to electricity. Marks apparently envisions a bank of such antennas mounted on a satellite for generating electricity more efficiently than photovoltaic devices. Such a process with respect to light energy is conceivable because the satellite is outside the otherwise troublesome scattering and absorption processes of the atmosphere and because the satellite is sufficiently far from the sun to prevent overheating. The marks concept, however, is probably not workable within the atmosphere since the light source must be very hot and positioning of the small antennas too close to the source would cause destructive heating, while positioning the antennas at a distance too far from the source would lead to the indicated light scattering and absorption in the intervening space.
Thus, the apparatus of U.S. Pat. No. 4,445,050 may ultimately not be more efficient than the conventional two step processes for converting heat from a heat source by expanding steam and driving a turbine and generator, since electricity obtained at a satellite must be beamed back to earth before being usable.